1. Technical Field
The present invention relates to surgical lasers, and more particularly to handpieces used in connection with surgical lasers.
2. Background Information
Surgical lasers have become as much a part of a typical surgeon's tools as are conventional scalpels. They are useful in a broad range of applications to coagulate, vaporize, excise or anastomose appropriate tissues. A common neodymium yttrium aluminum garnet (Nd:YAG) laser, for example, is widely used to facilitate removal of tissue with very little bleeding.
Conventional surgical lasers involve transmission of laser energy from a laser source through a fiber optic waveguide and out through a lens structure optically coupled to the end of the fiber optic. The lens structure focuses laser energy at a point spaced a short distance from the tip of the lens structure. In use, the lens structure is brought close to target tissue,.so as to bring the focused beam to bear upon the tissue.
Fiber optic waveguides are generally sheathed along their length in one or more layers of protective materials in order to protect the fiber from damage and to guard against escape of laser energy except at the tip. A sheathed fiber optic waveguide is generally referred to as a "dressed" fiber. Most fibers used in surgical lasers have a very small diameter, usually in the range of about 400 to 1000 microns. An advantage of fiber optic waveguides is their significant degree of flexibility, making it easy for a physician to manipulate the "cutting" tip without significant impediment from the trailing fiber. Although both flexibility and a small diameter are important to the function of a surgical laser, these properties make it necessary to provide a handpiece to support fiber optic and thereby give the surgeon a more comfortable and rigid gripping surface.
More recently, developments in laser technology have led to the use of contact tip laser systems in place of traditional noncontact laser systems. A particularly efficient and economical contact tip laser system utilizes a fiber optic provided with a unitary tip in a tapered or spherical (also referred to as "orbicular") shape. Unfortunately, being formed from fiber optic material, unitary contact tips are subject to damage or to breakage when used roughly. This is a problem of particular concern in applications such as orthopedics.
Orthopedic surgery often involves repair of damaged joints. A movable and load-bearing joint, such as the knee, is composed of a relatively complex network of interworking elements in order to accommodate the stresses associated with everyday movements and activities. The ends of the bones in a joint are capped with cartilage and a tough fibrous capsule to reduce friction and to absorb shock. A movable joint is provided with a system of tendons and ligaments to tie everything relatively tightly together. Large joints such as the knee also contain small fluid-filled sacs, called bursas, which act as shock absorbers. The fibrous capsule, tendons, ligaments and bursas are lined with synovial tissue, which excretes synovial fluid to lubricate the moving parts of the joint.
It will be appreciated that a typical joint does not readily accommodate insertion of a surgical laser fiber, even when small diameter fibers are used. Often, the surgeon must exert significant force on the handpiece in order to force the tip of the fiber around the various tendons and ligaments in order to reach, for example, a damaged piece of cartilage at a bone surface. Often, these movements will break the typically spherical contact tip off, leaving it in the patient's joint. A surgeon who performs procedures such as orthopedics is faced with the unpleasant alternatives of either accepting the risk that a contact tip will break off inside the patient, or switching to use of a more expensive and less efficient surgical laser system not utilizing a unitary contact laser tip.